Cerkniško jezero / Lago Circogno, view of the lake from the top of Slivnica, known as the Mountain of Witches. September 2017.

It is an ephemeral karst lake, ie it exists or does not exist in relation to the functioning or not of the siphons that empty the lake in the subsoil, it has no emissaries on the surface. The basin is also filled in relation to the water flow and can reach 38 km² of surface, becoming the largest lake in Slovenia, flooding cultivated fields and reaching the villages of the valley. But it can also dry up almost completely.